Alterations in the hypothalamic-pituitary-adrenal axis (HPAA) have been reported during the acute and chronic intake of ethanol as well as during the ethanol withdrawal syndrome. The integrity of the HPAA has typically been evaluated by the determination of plasma ACTH and cortisol following the administration of dexamethasone, subsequent to CRH stimulation, or diurnal rhythms. Specific binding sites for corticotrophin-releasing hormone (CRH) have recently been demonstrated in peripheral tissues and red blood cells (RBCs). Glucocorticoids have been demonstrated to alter CRH binding in peripheral tissues, and ethanol exposure causes a corresponding decrease in CRH binding sites on rat RBCs and anterior pituitary membranes. Therefore, it is thought that CRH binding to RBCs may provide an important clinical tool to indirectly assess CRH receptor levels in the pituitary gland. The determination of CRH binding sites on human RBCs from alcoholics (abstinent at least three weeks, N=17) and normal controls (N=17) at 8 AM and 8 PM have demonstrated increased CRH binding at 8 AM compared to 8 PM. Also, all alcoholics (with one exception) had significantly higher CRH binding in both the morning and evening that did normal controls. RBCs from the children of alcoholics and non-alcoholics have been obtained to determine if CRh binding sites are altered prior to the toxic effects of chronic alcohol use. CRH binding sites on RBCs and plasma cortisol and plasma cortisol and ACTH have also been evaluated every four for twenty hour hours on normal controls and alcoholics during withdrawal. Preliminary data demonstrate a diurnal rhythm of RBC-CRH binding with a peak at 2 AM and a trough at 2 PM.